More and more electronic devices such as mobile phones, MP3 players, Personal Digital Assistants (PDAS) are becoming smaller and smaller while having more and more information stored and/or accessible through them. Users are relying on these devices and becoming all the more dependant on them. Due to the devices' complexity they can sometimes be difficult for a user to learn and understand. There is a plethora of functionalities, features, applications and shortcuts available through a wide variety of user inputs such as touch input, key pad input, stylus input and recently also sensor based input such as tap input or tilting movement input using accelerometers. The sheer amount of possibilities can thus become bewildering to a user and increase the effort required to learn and understand the device significantly.
The environments in which these devices are used are also becoming more and more hectic with higher demands on fast access and multitasking, and not only in a professional environment but also in private and social environments. For example a user should be able to read a book, while holding a grocery bag in a rattling subway train and still be able to access the information stored in the device for the device to live up to the many requirements posed upon it by a user buying and using the device. This requires that the device is simple to learn and intuitive to use.